Solid forms of the compound, [5-(5-chloro-1H-pyrrolo[2,3-b]pyridin-3-ylmethyl)-pyridin-2-yl]- (6-trifluoromethyl-pyridin-3-ylmethyl)-amine HC1 salt (Compound I) and its free base, active on the receptor protein kinases c-Kit and/or c-Fms and/or Flt3, were prepared and characterized. Also provided are methods of using the solid forms.Las formas sólidas del compuesto, sal HCI de [5-(5-cloro-1H-pirrol o[2,3-b]piridin-3-ilmetil)-piridin-2-il]-(6-trifluorometil-piridi n-3-ilmetil)amina (Compuesto I) y su base libre, activa en las proteínas quinasas del receptor de c-Kit y/o c-Fms y/o FIt3, se preparan y se caracterizan. También se proporcionan métodos para usar las formas sólidas.